Ah. Preference is different from human perceptual hearing rules, the latter of which is why we have things like deciBels and the like. I can't speak to preference other than my own.
Most tube amps, to my understanding, have
more higher ordered harmonics than do most solid state amps. But they also have much greater 2nd and 3rd harmonics. Its well known that the 3rd can mask higher orders in loudspeaker design; I have to assume that whatever makes the harmonic isn't going to change the ear's masking principle
Since its so easy to show how sensitive the ear is to higher orders, why then does a tube amp have the property of 'smoothness' that so many audiophiles say they do? It could be confirmation bias, but I've seen such dramatic comparisons in this regard and also based on my own experience as a designer of 50 years that the logical and simpler answer (per Mr. Occam) is simply that the higher ordered harmonics of the tube amps are masked.